U.S. patent number 6,361,717 [Application Number 09/488,422] was granted by the patent office on 2002-03-26 for sterically stabilized second-order nonlinear optical chromophores and devices incorporating the same.
This patent grant is currently assigned to Pacific Wave Industries, Inc.. Invention is credited to Larry R. Dalton, Harold R. Fetterman, Aaron W. Harper, Joseph Michael, Albert S. Ren, William Steier, Chuanguang Wang, Fang Wang, Cheng Zhang.
United States Patent |
6,361,717 |
Dalton , et al. |
March 26, 2002 |
Sterically stabilized second-order nonlinear optical chromophores
and devices incorporating the same
Abstract
Sterically stabilized second-order nonlinear optical
chromophores and devices incorporating the same are embodied in a
variety of chromophore materials. An exemplary preferred
chromophore includes an electron donor group, an electron acceptor
group and a bridge structure therebetween, with the electron
acceptor group being double bonded to the bridge structure. In a
preferred embodiment, the bridge structure also includes at least
one bulky side group. Another exemplary preferred chromophore
includes an electron donor group, an electron acceptor group and a
ring-locked bridge structure between the electron donor group and
the electron acceptor group. The bridge structure comprises, for
example, two protected alicyclic rings or ring-locked trienone.
Another exemplary preferred chromophore includes an electron donor
group, a ring-locked tricyano electron acceptor group, and a bridge
structure therebetween. In a preferred embodiment, the electron
acceptor group comprises an isophorone structure.
Inventors: |
Dalton; Larry R. (Bainbridge
Island, WA), Zhang; Cheng (Los Angeles, CA), Wang;
Chuanguang (Los Angeles, CA), Fetterman; Harold R.
(Pacific Palisades, CA), Wang; Fang (Highland Park, NJ),
Steier; William (San Marino, CA), Harper; Aaron W.
(Monterey Park, CA), Ren; Albert S. (Los Angeles, CA),
Michael; Joseph (Los Angeles, CA) |
Assignee: |
Pacific Wave Industries, Inc.
(Los Angeles, CA)
|
Family
ID: |
23939649 |
Appl.
No.: |
09/488,422 |
Filed: |
January 20, 2000 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
122806 |
Jul 27, 1998 |
6067186 |
|
|
|
Current U.S.
Class: |
252/582;
359/328 |
Current CPC
Class: |
C08K
5/0041 (20130101); C09B 23/0066 (20130101); C09B
23/0075 (20130101); C09B 23/0091 (20130101); C09B
23/145 (20130101); G02F 1/3612 (20130101); G02F
1/3614 (20130101); G02F 1/3615 (20130101) |
Current International
Class: |
C09B
23/14 (20060101); C09B 23/01 (20060101); C09B
23/00 (20060101); C08K 5/00 (20060101); G02F
001/35 (); F21V 009/00 () |
Field of
Search: |
;252/582 ;359/328 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
L R. Dalton et al., "From molecules to opto-chips: organic
electro-optic materials," J. Mater. Chem., 1999, 9, 1905-1920.
.
N. Nemoto et al., "Novel Types of Polyesters Containing
Second-Order Nonlinear Optically Active Chromophores with High
Density," Macromolecules 1996, 29, 2365-2371. .
Z. Sekkat et al., "Room-Temperature Photoinduced poling and Thermal
Poling of a Rigid Main-Chain Polymer with Polar Azo Dyes in the
Side Chain," Chem. Mater. 1995, 7, 142-147. .
S. Yokoyama et al., "Second harmonic generation of dipolar dendrons
in the assembled thin films," Thin Solid Films 331 (1998) 248-253.
.
C. Zhang et al., "Chromophore Incorporating Fluorinated Aromatic
Polyester for Electro-optic Applications," Polymer Preprints 40(2)
Aug. 1999. .
Y. Zhang et al., "A new hyperbranched polymer with polar
chromophores for nonlinear optics" Polymer (1997), 38(12),
2893-2897. .
D. G. Girton, et al., "20 GHz electro-optic polymer Mach-Zehnder
modulator", Applied Physics Letters, vol. 58, No. 16, pp. 1730-1732
(1991). .
D. M. Burland, et al., "Second-Order Nonlinearity in Poled-Polymer
Systems", Chemical Reviews,, vol. 94, pp. 31-75 (1994). .
S. Kalluri, "Improved poling and thermal stability of sol-gel
nonlinear optical polymers"Applied Physics Letters, vol. 65, No.
21, pp. 2651-2653 (1994). .
I. Cabrere, et al., "A New Class of Planar-Locked Polyene Dyes for
Nonlinear Optics", Advanced Materials, vol. 6, pp. 43-45 (1994).
.
W. Wang, "40-GHz Polymer Electrooptic Phase Modulators", IEEE
Photonics Technology Letters, vol. 7, No. 6, pp. 638-640 (1995).
.
L. R. Dalton, et al., "Sythesis and Processing of Improved Organic
Second-Order Nonlinear Optical Materials for Applications in
Photonics", Chemistry of Materials, vol. 7, pp. 1060-1081 (1995).
.
S. Kalluri, "Monolithic Integration of Waveguide Polymer
Electrooptic Modulators on VLSI Circuitry", IEEE Photonics
Technology Letters, vol. 8, No. 5, pp. 644-646 (1996). .
Y. Shi, et al., "Fabrication and Characterization of High-Speed
Polyurethane-Disperse REd 19 Integrated Electrooptic Modulators for
Analog System Applications", IEEE Journal of Selected Topics in
Quantum Electronics, vol. 2, No. 2, pp. 289-299 (1996). .
C. Shu, et al., "Synthesis of second-order nonlinear optical
chromophores with enhanced thermal stability: a conformation-locked
trans-polyene approach", Chemical Communication, pp. 2279-2280
(1996). .
A. Chen, "Optimized Oxygen Plasma Etching of Polyurethane-Based
Electro-optic Polymer for Low Loss Optical Waveguide Fabrication",
Journal of Electrochemical Society, vol. 143, No. 11, pp. 3648-3651
(1996). .
D. X. Zhu, "Noncollinear four-wave mixing in a broad area
semiconductor optical amplifier", Applied Physics Letters, vol. 70,
No. 16, pp. 2082-2084 (1997). .
D. Chen, "Demonstration of 110GHz eletro-optic polymer modulators",
Applied Physics Letters, vol. 70, No. 25, pp. 3335-3337 (1997).
.
L. Dalton, "Polymeric electro-optic modulators", Chemistry &
Industry, pp. 510-514 (1997). .
S. Ermer, "Synthesis and Nonlinearity of Triene Chromophores
Containing the Cyclohexen Ring Structure", Chemistry of Materials,
vol. 9, pp. 1437-1442 (1997). .
A. Harper, et al., "Translating microscopic optical nonlinearity
into macroscopic optical nonlinearity: the role of
chromophore-chromophore electrostatic interactions", Journal of
Optical Society of America: B, vol. 15, No. 1, pp. 329-337 (1998).
.
A. Chen, et al., "Low-V.sub..pi. electro-optic modular with a
high-.mu..beta. chromophore and a constant-bias field", Optics
Letters, vol. 23, No. 6, pp. 478-480 (1998). .
C. Shu, et al., Nonlinear Optical Chromophores with
Configuration-Locked Polyenes Possessing Enhanced Thermal Stability
and Chemical Stability, Chemistry of Materials, vol. 10, pp.
3284-3286 (1998)..
|
Primary Examiner: Tucker; Philip
Attorney, Agent or Firm: Henricks, Slavin & Holmes
LLP
Government Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND
DEVELOPMENT
This invention was made with support from the government of the
United States of America under Contracts F49620-97-C-0064,
F49620-97-1-0307, F49620-97-1-0491, F49620-97-C-0064,
F49620-98-C-0059, F49620-98-C-0077, F49620-99-0040 awarded by the
United States Air Force. The government of the United States of
America has certain rights in this invention as provided by these
contracts.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. patent
application Ser. No. 09/122,806 entitled "New Class of High
Hyperpolarizability Organic Chromophores and Process for
Synthesizing the Same" filed on Jul. 27, 1998, now U.S. Pat. No.
6,067,186.
Claims
We claim:
1. A nonlinear optical device comprising: an active element
including a chromophore formed as: ##STR1## wherein D is an
electron donor group; wherein A is an electron acceptor group;
wherein R.sub.1 to R.sub.9 =H, --C.sub.n H.sub.2n+1, n=1-30
including primary, secondary, tertiary and any branched alkyl
groups, or any alkyl group with 1-30 carbon atoms functionalized
with one or more of the following functional groups: hydroxy,
ether, ester, amino, silyl, siloxy.
2. A nonlinear optical device comprising: an active element formed
from a chromophore including an electron donor group, an electron
acceptor group, and a bridge structure between the electron donor
group and the electron acceptor group, the bridge structure
including an alicyclic ring; wherein the electron acceptor group is
connected to the bridge structure with a conjugated diene.
3. The nonlinear optical device of claim 2 wherein the bridge
structure includes at least one side group.
4. The nonlinear optical device of claim 2 wherein the chromophore
is formed in a polymer matrix.
5. A nonlinear optical device comprising: an active element formed
from a chromophore including an electron donor group (D), an
electron acceptor group (A), and a ring-locked bridge structure
between the electron donor group and the electron acceptor group;
wherein the ring-locked bridge structure is formed as ##STR2##
wherein R.sub.1 to R.sub.3 =H, --C.sub.n H.sub.2n+1, n=1-30
including primary, secondary, tertiary and any branched alkyl
groups, or any alkyl group with 1-30 carbon atoms functionalized
with one or more of the following functional groups: hydroxy,
ether, ester, amino, silyl, siloxy.
6. The nonlinear optical device of claim 5 wherein the chromophore
is formed in a polymer matrix.
7. A nonlinear optical device comprising: an active element formed
from a chromophore including an electron donor group (D), an
electron acceptor group (A), and a ring-locked bridge structure
between the electron donor group and the electron acceptor group;
wherein the ring-locked bridge structure is formed as ##STR3##
wherein R.sub.1 to R.sub.6 =H, --C.sub.n H.sub.2n+1, n=1-30
including primary, secondary, tertiary and any branched alkyl
groups, or any alkyl group with 1-30 carbon atoms functionalized
with one or more of the following functional groups: hydroxy,
ether, ester, amino, silyl, siloxy.
8. The nonlinear optical device of claim 7 wherein the chromophore
is formed in a polymer matrix.
9. A nonlinear optical device comprising: an active element formed
from a chromophore including an electron donor group (D), an
electron acceptor group (A), and a ring-locked bridge structure
between the electron donor group and the electron acceptor group;
wherein the ring-locked bridge structure is formed as ##STR4##
wherein R.sub.1 to R.sub.9 =H, --C.sub.n H.sub.2n+1, n=1-30
including primary, secondary, tertiary and any branched alkyl
groups, or any alkyl group with 1-30 carbon atoms functionalized
with one or more of the following functional groups: hydroxy,
ether, ester, amino, silyl, siloxy.
10. The nonlinear optical device of claim 9 wherein the chromophore
is formed in a polymer matrix.
11. A nonlinear optical device comprising: an active element formed
from a chromophore including an electron donor group, a ring-locked
tricyano electron acceptor group, and a bridge structure between
the electron donor group and the ring-locked tricyano electron
acceptor group.
12. The nonlinear optical device of claim 11 wherein the
ring-locked tricyano electron acceptor group is connected to the
bridge structure with a conjugated diene.
13. The nonlinear optical device of claim 11 wherein the
ring-locked tricyano electron acceptor group comprises an
isophorone structure.
14. The nonlinear optical device of claim 11 wherein the bridge
structure comprises a fused ring system.
15. The nonlinear optical device of claim 11 wherein the
chromophore is formed in a polymer matrix.
16. The nonlinear optical device of claim 11 wherein the
ring-locked tricyano electron acceptor group comprises: ##STR5##
wherein R.sub.1 to R.sub.6 =H, --C.sub.n H.sub.2n+1, n=1-30
including primary, secondary, tertiary and any branched alkyl
groups, or any alkyl group with 1-30 carbon atoms functionalized
with one or more of the following functional groups: hydroxy,
ether, ester, amino, silyl, siloxy.
17. A nonlinear optical device comprising: an active element formed
from a chromophore including an electron donor group, an electron
acceptor group, and a bridge structure between the electron donor
group and the electron acceptor group, the bridge structure
including a bithiophene unit formed as ##STR6## wherein R.sub.1 to
R.sub.4 =H, --C.sub.n H.sub.2n+1, n=1-30 including primary,
secondary, tertiary and any branched alkyl groups, or any alkyl
group with 1-30 carbon atoms functionalized with one or more of the
following functional groups: hydroxy, ether, ester, amino, silyl,
siloxy; wherein the bridge structure further includes a 1,3-dioxin
derivative formed as ##STR7## wherein R.sub.1, and R.sub.2 =H,
--C.sub.n H.sub.2n+1, n=1-30 including primary, secondary, tertiary
and any branched alkyl groups, or any alkyl group with 1-30 carbon
atoms functionalized with one or more of the following functional
groups: hydroxy, ether, ester, amino, silyl, siloxy.
18. A nonlinear optical device comprising: an active element formed
from a chromophore including an electron donor group, an electron
acceptor group, and a bridge structure between the electron donor
group and the electron acceptor group, the bridge structure
including a bithiophene unit formed as ##STR8## wherein R.sub.1 to
R.sub.4 =H, --C.sub.n H.sub.2n+1, n=1-30 including primary,
secondary, tertiary and any branched alkyl groups, or any alkyl
group with 1-30 carbon atoms functionalized with one or more of the
following functional groups: hydroxy, ether, ester, amino, silyl,
siloxy; wherein the electron acceptor group comprises a tricyano
electron acceptor group comprising: ##STR9##
19. The nonlinear optical device of claim 17 wherein the
chromophore is formed in a polymer matrix.
20. A nonlinear optical device comprising: an active element
including a chromophore formed as: ##STR10## wherein R groups are
independently selected from H, or any perhalogenated, halogenated
or non-halogenated aliphatic or aromatic group with 1-30 carbon
atoms functionalized with zero or more of the following functional
groups: hydroxy, ether, ester, amino, silyl, and siloxy.
21. The nonlinear optical device of claim 18 wherein the
chromophore is formed in a polymer matrix.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to nonlinear optical chromophores
and, more particularly, pertains to sterically stabilized
second-order nonlinear optical chromophores and devices
incorporating the same.
2. Description of the Related Art
Organic second-order nonlinear optical (NLO) materials have
received increasing attention for applications involving signal
processing and telecommunications. One of the challenges in this
field is to design and synthesize second-order NLO chromophores
(the active components of second-order nonlinear optical materials)
that simultaneously possess large first molecular
hyperpolarizabilities (.beta.), good chemical and thermal
stability, and optical transparency at optical communication
wavelengths (1.3 and 1.55 .mu.m). Chromophore intermolecular
electrostatic interactions prevent the simple scaling of molecular
optical nonlinearity into macroscopic optical nonlinearity. Such
interactions strongly attenuate the efficient induction of acentric
chromophore order (hence, electrooptic activity) by electric field
poling or self-assembly methods. Chromophores with .beta. values
many times those of the well-known Disperse Red 19 dye are thus
required to obtain electrooptic coefficients comparable to or
higher than those of the leading commercial material crystalline
lithium niobate.
The value of .beta. for a chromophore can be increased by using a
diene moiety in place of thiophene in the conventional
phenylethenylenethiophene .pi.-conjugated bridge. Moreover, this
enhancement in .beta. can be accomplished without an increase in
the wavelength of the charge-transfer absorption .lambda..sub.max.
However, the resulting phenylpolyene bridge has poor thermal
stability unless the polyene structure is sterically protected. The
synthesis of various sterically-protected (ring-locked)
phenylpolyene chromophores involves cyclic enones such as
isophorone, verbenone and double-ring locked dienone as starting
materials and intermediates. The Knovenegal coupling reaction
between enones and electron acceptors is the critical step in both
backward and forward methods reported. The low reactivity of enone
severely limits the choice of acceptor to only a few molecules
including malononitrile, isoxazolone, and thiobarbituric acid and
therefore has become the bottleneck in the development of
ring-locked phenylpolyene-bridged high .beta. chromophores.
SUMMARY OF THE INVENTION
A new class of ring-locked aminophenylpolyenal donor-bridges has
been developed. These new donor-bridges, according to the present
invention, have very high Knovenegal reactivity and have been
coupled with a variety of acceptors bearing acidic methyl or
methylene groups (including the most desired TCF and TCI type of
acceptors shown in FIG. 11) to obtain a new class of second-order
NLO chromophores. This methodology broadens the scope of
polyene-bridged chromophores without significantly sacrificing
thermal stability or optical transparency. This synthetic approach
leads to the development of device-quality NLO chromophores (shown
in FIG. 1) possessing .mu..beta. values (where .mu. is the
chromophore dipole moment) of 15,000.times.10.sup.-48 esu or
greater at 1.9 .mu.m as determined by the electric field induced
second harmonic generation (EFISH) technique.
A variety of different molecular structures are possible for the
chromophores of the present invention. An exemplary preferred
chromophore according to the present invention includes an electron
donor group, an electron acceptor group and a bridge structure
therebetween, with the electron acceptor group being double bonded
to the bridge structure. In a preferred embodiment, the bridge
structure also includes at least one bulky side group.
Another exemplary preferred chromophore according to the present
invention includes an electron donor group, an electron acceptor
group and a ring-locked bridge structure between the electron donor
group and the electron acceptor group. The bridge structure
comprises, for example, two protected alicyclic rings or
ring-locked trienone.
Another exemplary preferred chromophore according to the present
invention includes an electron donor group, a ring-locked tricyano
electron acceptor group, and a bridge structure therebetween. In a
preferred embodiment, the electron acceptor group comprises an
isophorone structure.
Another exemplary preferred chromophore according to the present
invention includes an electron donor group, an electron acceptor
group, and a bridge structure therebetween, with the bridge
structure including a bithiophene unit. In a preferred embodiment,
the bridge structure further includes a modified isophorone
unit.
The NLO materials of the present invention are suitable for a wide
range of devices. Functions performed by these devices include, but
are not limited to, the following: electrical to optical signal
transduction; radio wave to millimeter wave electromagnetic
radiation (signal) detection; radio wave to millimeter wave signal
generation (broadcasting); optical and millimeter wave beam
steering; and signal processing such as analog to digital
conversion, ultrafast of signals at nodes of optical networks, and
highly precise phase control of optical and millimeter wave
signals.
DESCRIPTION OF THE DRAWINGS
Other objects, features and advantages of the invention will become
readily apparent upon reference to the following detailed
description when considered in conjunction with the accompanying
drawings, in which like reference numerals designate like parts
throughout the figures thereof, and wherein:
FIG. 1 illustrates the basic structure of CLD, GLD and ZLD
chromophores according to the present invention;
FIG. 2 illustrates exemplary preferred CLD chromophores according
to the present invention;
FIG. 3 illustrates an exemplary preferred method according to the
present invention for synthesizing a CLD chromophore;
FIG. 4 illustrates exemplary preferred CLD chromophores with alkyl
derivative at the middle ring;
FIG. 5 illustrates an exemplary preferred method according to the
present invention for synthesizing a sterically modified CLD
chromophore;
FIG. 6 illustrates an exemplary preferred method according to the
present invention for synthesizing a GLD chromophore;
FIG. 7 illustrates an exemplary preferred method according to the
present invention for synthesizing a ZLD chromophore;
FIG. 8 illustrates exemplary preferred chromophores containing
bithiophene units and modified isophorone units according to the
present invention;
FIG. 9A illustrates the synthesis, thermal, and optical properties
of chromophores incorporating bithiophene units according to the
present invention;
FIG. 9B illustrates an exemplary preferred synthetic scheme for the
chromophore of FIG. 9A;
FIG. 10 illustrates an exemplary preferred method of bridge
modification by bithiophene insertion and isophorone modification
according to the present invention;
FIG. 11 illustrates exemplary preferred ring-locked tricyano
electron acceptors for the chromophores according to the present
invention;
FIG. 12 illustrates a version of CLD chromophore according to the
present invention where the cyanofuran acceptor has been modified
by replacement of the furan oxygen atom with a isophorone
structure;
FIG. 13 illustrates exemplary preferred alternative donor
structures for the FTC, CLD and GLD chromophores according to the
present invention;
FIGS. 14A and 14B illustrate exemplary preferred FTC chromophores
with modified donor structures according to the present
invention;
FIG. 15 illustrates the preparation of an exemplary preferred
CLD-containing polyester polymer according to the present
invention;
FIG. 16 illustrates the variation of electrooptic activity (divided
by molecular polarizability) versus chromophore concentration in
the polymer lattice for two values of the electric poling
field;
FIG. 17 illustrates an exemplary preferred electrooptic device
employing a constant electric field bias, the device incorporating
a chromophore material the present invention;
FIG. 18 illustrates an exemplary preferred Mach Zehnder modulator
incorporating a chromophore material of the present invention;
and
FIG. 19 illustrates the use of a chromophore material of the
present invention (in the form of microstrip lines) in a microwave
phase shifter of the type employed in optically controlled phased
array radars.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following is a detailed description of the best presently known
mode of carrying out the invention. This description is not to be
taken in a limiting sense, but is made merely for the purpose of
illustrating the general principles of the invention.
This application is a continuation-in-part of U.S. patent
application Ser. No. 09/122,806 entitled "New Class of High
Hyperpolarizability Organic Chromophores and Process for
Synthesizing the Same" filed on Jul. 27, 1998, the disclosure of
which is incorporated herein by reference in its entirety.
Referring to FIG. 1, three molecular chromophore structures
according to the present invention are identified by their
abbreviated names: CLD, GLD and ZLD. Each chromophore includes an
electron donor group ("D"), an electron acceptor group ("A") and a
bridge structure therebetween. As shown in FIG. 1, in the exemplary
preferred chromophores, the electron acceptor group is connected to
the ring-locked polyene bridge structure with a conjugated diene.
See, C. Zhang, A. S. Ren, F. Wang, J. Zhu, L. Dalton, "Synthesis
and Characterization of Sterically Stabiliized Second-Order
Nonlinear Optical Chromophores", Chem. Mater. 1999, 11, 1966-1968,
which is incorporated herein by reference. Within the scope of the
present invention, it is also contemplated that the electron donor
group can be double bonded to the bridge structure.
Exemplary preferred structures for the electron donor group are
shown in FIGS. 1 and 13. In FIG. 1, R.sub.1 to R.sub.9 =H,
--C.sub.n H.sub.2n+1, n=1-30 including primary, secondary, tertiary
and any branched alkyl groups, or any alkyl group with 1-30 carbon
atoms functionalized with one or more of the following functional
groups: hydroxy, ether, ester, amino, silyl, siloxy.
Exemplary preferred structures for the electron acceptor group are
shown in FIG. 11. The electron acceptor groups preferably have
five-member or six-member rings. However, rings with seven or more
members can also be employed.
Generally, it has been observed that dipole moment and molecular
hyperpolarizability increase from CLD to ZLD. Final device
performance (electrooptic activity) is related to the product of
dipole moment and hyperpolarizability. A corresponding increase in
electrooptic activity over this series has also been observed. For
example, for measurements carried out at 1.06 microns wavelength,
the following electrooptic activities coefficients were observed:
55 pm/V (FTC), 85 pm/V (CLD), 110 pm/V (GLD). These values were
obtained for the low dielectric polymer matrix
poly-(methylmethacrylate), PMMA. Somewhat larger electrooptic
coefficients were observed in polymer matrices (e.g., amorphous
poly(carbonate), APC) of higher dielectric constant.
A large number of variations of the CLD, GLD and ZLD structures
have been synthesized, characterized, and utilized in the
fabrication of prototype devices by modifying the starting
materials in the general synthetic schemes presented herein and in
U.S. patent application Ser. No. 09/122,806. Exemplary preferred
CLD chromophores are shown in FIG. 2.
Synthesis of CLD Chromophore
Referring to FIG. 3, an exemplary preferred method for synthesizing
CLD is illustrated. The exemplary preferred method for synthesis is
described below.
A mixture of 1.815 mol of
p-N,N-bis(2-hydroxyethyl)aminobenzaldehyde, 2.178 mol, 301 g of
isophorone, 1 L of EtOH, and 2.1 mol of sodium ethoxide was stirred
at 50.degree. C. for 15 h. The reaction was stopped by adding 50 g
of water. Ethanol was evaporated in vacuo and product crystallized
out. The product was collected by filtration, washed with water. It
was vacuumed to remove water and then recrystallized from EtOAc to
give 90% yield. Mass: 329.200, found 329.199.
TBDMS protection: A mixture of 45.4 g, 138 mol of the above
product, 80 g DMF, 42 g imidazole and 46 g t-butyldimethylsilyl
chloride was stirred at 60.degree. C. for 6 h. The mixture was then
poured to water and extracted with hexane. The extract was
condensed and the residual was purified by column chromatography to
give 72.7 g product: 94.5% yield. Crystals from hexane had a
melting point of 106.5-108.degree. C. Elemental analysis: calc. C,
68.88; H, 9.94; N, 2.51; Found C, 69.04, H, 9.92; N 2.48.
Extension of ketone to aldehyde: A solution of 110 mmol, 13.77 g of
N-cyclohexylacetimine in 35 ml THF was added to 77 ml 1.5M
LDA/cyclohexane at -50 C. After the addition the mixture was warmed
up with an ice bath and then recooled to -78 C. A solution of 61.35
g of the above ketone in 105 ml THF was added. The mixture was then
warm up in air and then acidified with dilute acetic acid solution
and stirred at room temperature for 11 h. After usual work up, the
crude product was purified by column chromatography to give 26.56 g
pure product: 41.6% yield.
CLD-1: A mixture of 10.99 g of above aldehyde, 3.75 g of
2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran, 110 ml
anhydrous EtOH, 0.7 ml of 21 wt % EtONa/EtOH was refluxed for 4 h.
The product was collected by filtration and recrystallized from
ethanol to give 11.5 g chromophore: 80% yield. Elemental analysis:
calcd.: C, 70.63; H, 8.43; N, 7.32. Found: C, 70.66; H, 8.53; N,
7.36. .lambda..sub.max : 632.4 nm in dioxane, 692.2 nm in
CHCl.sub.3. Td 274.7.degree. C. by DSC (N.sub.2, 10.degree.
C./min).
A protonated version is synthesized by removing the TBMDS
protecting group. A number of variants of this structure have been
synthesized by use of modified starting materials following the
general reaction scheme presented above.
Variations to the chromophores have been made to improve
electrooptic activity either by sterically inhibiting unwanted
intermolecular electrostatic interactions, by improving the
electron-withdrawing characteristics of the acceptor end of the
chromophores, by improving the electron donating characteristics of
the donor end of the chromophore, or by improving electron
communication of the bridge segment of the chromophore.
Referring to FIG. 4, a representative example of steric
modification of the bridge segment of the CLD chromophore shows the
addition of a bulky side group (alkyl derivative at the middle
ring) to reduce electrostatic interaction. It should be understood,
however, that other side groups can be added. A plurality of bulky
side groups, e.g., branched or tertiary side groups, can also be
added to each bridge segment.
Synthesis of Sterically Modified CLD Chromophore
An exemplary preferred method for synthesizing a sterically
modified CLD chromophore is illustrated in FIG. 5. The exemplary
preferred method for synthesis is described below.
2-Hexyl-isophorone
This compound was synthesized according a literature method (Stork,
G. Benaim, J. J. Am. Chem. Soc. 1971, 5938-5939.) from isophorone
in 55% yield. .sup.1 H NMR (CDCl.sub.3): .delta.2.29 (t, 6.32 Hz,
2H), 2.23 (s, 2H), 1.92 (s, 2H), 1.30 (m, 8H), 1.00 (s, 6H), 0.88
(t, 6.42 Hz, 3H). .sup.13 C NMR (CDCl.sub.3): .delta.198.55,
151.93, 134.53, 51.16, 46.75, 32.43, 31.56, 29.25, 28.90, 27.99,
24.80, 22.41, 21.04, 13.88. Anal. Calcd. for C.sub.15 H.sub.26
O.sub.1 : C, 81.02; H, 11.79; Found: C, 81.18; H, 11.87.
3-[p-N,N-Bis(2-t-butyldimethylsiloxyethyl)aminostyryl]-5,5-dimethyl-2-hexyl
-cyclohex-2-enone
Potassium t-butoxide (30.32 g, 97%, 0.262 mol.) was added to a
solution of
p-N,N-Bis(2-t-butyldimethylsiloxyethyl)aminobenzaldehyde (, 53.4 g,
0.122 mol.) and 2-hexyl-isophorone (compound 10, 26.6 g, 0.118
mol.) in diglyme (200 mL, KOH dried) over 3 min. Ice bath was used
to keep the temperature below 50.degree. C. The reaction mixture
was stirred at room temperature for 25 min. and then was poured to
dilute acetic acid (0.28 mol HOAc in 200 mL of water). The extra
acid was neutralized saturated aqueous sodium bicarbonate. The
organic layer was separated, washed with water, dried with
magnesium sulfate and rotovapped to dryness. The residue was
purified by a silica gel column using ethyl acetate/hexane (1/20,
v/v) to afford 8.33 g red thick oil: yield 22% based on reacted
starting material. Only about starting materials reacted. .sup.1 H
NMR (CDCl.sub.3): .delta.7.36 (d, 8.81 Hz, 2H), 7.14 (d, 16.06 Hz,
1H), 6.88 (d, 16.09 Hz, 1H), 6.69 (d, 8.91 Hz, 2H), 3.78 (t, 6.06
Hz, 4H), 3.56 (t, 5.89 Hz, 4H), 2.53 (br, 2H), 2.48 (s, 2H), 2.29
(s, 2H), 1.33 (m, 8H), 1.05 (s, 6H), 0.90 (s, 18H), 0.04 (s, 12H)
ppm. .sup.13 C NMR (CDCl.sub.3): .delta.198.87, 148.41, 147.67,
134.47, 134.19, 128.52, 124.38, 121.71, 111.54, 60.21, 53.42,
51.37, 39.82, 32.27, 31.65, 29.90, 29.37, 28.39, 25.79, 24.30,
22.54 ppm.
TBDMS Protected, Hexyl Derivatized Donor-bridge
A solution of lithium diisopropylamine (4.7 mL 1.5M in THF, 7.05
mmol.) in THF (12 mL) was cooled to -20.degree. C.
N-cyclohexylacetimine (6.7 mmol.) was added and the mixture was
allowed to warm up to 0.degree. C. and was kept at the temperature
for 15 min. It was re-cooled to -20.degree. C. and
3-[p-N,N-Bis(2-t-butyldimethylsiloxyethyl)aminostyryl]-5,5-dimethyl-2-hexy
l-cyclohex-2-enone (4.31 g, 6.71 mmol., in 15 mL of THF) was added
over 3 min. It was stirred for 5 more min. and was stopped by
adding 1N acetic acid solution. The product was extracted with
hexane and the extract was washed with sodium bicarbonate solution,
dried with magnesium sulfate and rotovapped to dryness. The residue
was purified by a silica gel column using ethyl acetate/hexane
(1/20, v/v) to afford 0.55 g red oil product and recovered 3.45 g
starting material. The yield was 61% based on consumed starting
ketone. .sup.1 H NMR (CDCl.sub.3): .delta.10.13 (d, 8.22 Hz, 1H),
7.33 (d, 8.80 Hz, 2H), 7.15 (d, 15.54 Hz, 1H), 6.77 (d, 16.38 Hz,
1H), 6.68 (d, 9.13 Hz, 2H), 6.20 (d, 7.94 Hz, 1H), 3.78 (t, 5.84
Hz, 4H), 3.55 (t, 5.74 Hz, 4H), 2.68 (s, 2H), 2.52 (br, t, 2H),
2.38 (s, 2H), 1.34 (m, 8H), 1.01 (s, 6H), 0.89 (s, 18H), 0.04 (s,
12H) ppm. .sup.13 C NMR (CDCl.sub.3): .delta.191.53, 157.46,
148.14, 140.57, 133.16, 132.65, 128.23, 124.87, 123.47, 122.31,
111.59, 60.23, 53.43, 40.40, 39.38, 31.59, 30.15, 29.78, 29.52,
28.22, 27.26, 25.79, 22.57, 18.15, 14.03, -5.47 ppm. Exact mass
calcd. for C.sub.40 H.sub.69 N.sub.1 O.sub.3 Si.sub.2 : 668.493.
Found: 668.489.
Chromophore
Above aldehyde (0.55 g, 0.823 mmol.) and
2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (0.198
g, 0.988 mmol.) were dissolved in 5 mL of ethanol that contained 7
mg of sodium hydroxide. The solution was refluxed for 3.5 hours and
then 10 mL of water was added dropwise to precipitate out the
product. The crude product was collected by filtration, washed with
water, dried in vacuo, and purified by a silica gel column using
ethyl acetate/hexane (1/7 to 1/5, v/v) to give 245 mg pure product:
yield 35%. .sup.1 H NMR (CDCl.sub.3): .delta.8.06 (q, J.sub.1
=12.02 Hz, J.sub.2 =14.74 Hz, 1H), 7.36 (d, 8.89 Hz, 2H), 7.22 (d,
16.29 Hz, 1H), 6.88 (d, 15.79 Hz, 1H), 6.70 (8.78 Hz, 2H), 6.63 (d,
12.09 Hz, 1H), 6.35 (d, 14.96 Hz, 1H), 3.78 (t, 5.77 Hz, 4H), 3.57
(d, 5.83 Hz, 1H), 2.61 (br, t, 2H), 2.44 (s, 4H), 1.71 (s, 6H),
1.43 (br, m, 8H), 0.89 (s, 18H), 0.03 (s, 12H) ppm. .sup.13 C NMR
(CDCl.sub.3): .delta.176.35, 173.46, 155.48, 148.88, 145.13,
144.08, 135.16, 134.78, 128.94, 124.92, 124.27, 122.39, 115.82,
112.80, 112.06, 111.90, 111.77, 96.78, 93.93, 60.40, 55.68, 53.57,
40.87, 40.71, 31.78, 30.64, 30.18, 29.72, 28.43, 27.25, 26.70,
25.97, 22.76, 18.35, 14.24, -5.28 ppm. Exact mass calculated for
C.sub.51 H.sub.76 N.sub.4 O.sub.3 Si.sub.2 : 848.543. Found:
848.546.
In addition to the hexyl variant shown, other linear and branched
alkyl derivatives were synthesized and characterized. Also, the
methyl groups on the isophorone alicyclic ring were replaced by a
variety of longer alkyl groups. Both hydoroxylated (deprotected)
and TBDMS protected donor structures were prepared, characterized
and utilized.
Synthesis of GLD Chromophore
Referring to FIG. 6, an exemplary preferred method for synthesizing
the GLD chromophore is illustrated. The exemplary preferred method
for synthesis is described below.
The procedure for synthesizing GLD is essentially the same as the
CLD synthesis procedure shown in FIG. 3, except that two steps were
added to construct the fused ring system. The discussion of FIG. 3
is applicable with respect to the preparation of variants of this
theme.
Synthesis of ZLD Chromophore
Referring to FIG. 7, an exemplary preferred method for synthesizing
the ZLD chromophore is illustrated. The exemplary preferred method
for synthesis is described below.
Synthesis of ring-locked trienone: To a solution of 11 mmol of the
starting material (synthesized according C.-F. Shu et al, Chem.
Mater. 1998, 10, 3284) in 20 ml of anhydrous THF and 1.3 eq cooled
in ice bath, 4.77 ml 3M methylmagnesium bromide ether solution was
added over 2 min. After addition, the mixture was refluxed for 30
min. The mixture was acidified with 30 wt % aqueous acetic acid
solution and stirred at room temperature overnight. After usual
work up, the crude product was purified using to give 1.37 g pure
product, yield 52%. Recrystallization from hexane gave orange red
crystals with a mp of 135.5-137.5 C. Elemental analysis: Calcd. for
C17H22O: C, 84.25; H, 9.15;. Found: C, 83.96, H, 9.25.
The remaining steps are similar to those shown in FIG. 3.
Referring to FIG. 8, exemplary preferred chromophores according to
the present invention include bridge structures which have been
modified by the insertion of bithiophene units and modified
isophorone units. The synthesis, thermal, and optical properties of
chromophores incorporating bithiophene units are shown in FIG. 9A.
As illustrated, this modification provides an increased thermal
stability characteristic.
Synthesis of Chromophore Incorporating Bithiophene Units
Referring to FIG. 9B, an exemplary preferred method for
synthesizing the chromophore incorporating bithiophene units is
illustrated. The exemplary preferred method for synthesis is
described below.
3,3',5,5'-Tetrabromo-2,2'-bithiophene
Bromine (41.2 g, 257.8 mmol) was added dropwise to a solution of
2,2'-bithiophene (10 g, 60.2 mol) in 250 ml of chloroform at
0-5.degree. C. A light-yellow solid was formed gradually during the
addition. The mixture was stirred at room temperature overnight and
then refluxed for 2 h. After cooling to room temperature, 100 ml of
10% KOH aqueous solution was added. The resulting mixture was
extracted with chloroform to give the crude product.
Recrystallization from ethanol/CHCl.sub.3 (1:1) afforded a
light-yellow crystal in the yield of 87% (25.1 g). .sup.1 H-NMR
(CDCl.sub.3, ppm): .delta.7.05 (s, 2H).
3,3'-Dibromo-2,2'-bithiophene
A mixture of 3,3',5,5'-tetrabromo-2,2'-bithiophene (25 g, 52.3
mmol), ethanol (50 ml), water (50 ml) and glacial acetic acid (100
ml) was heated to reflux. Then the heating oil bath was removed,
and zinc powder (13.1 g, 200 mmol) was added in portions at such a
rate that the mixture continued to reflux. After the addition was
complete, heating was continued, the mixture was refluxed for
another 5 h and cooled down to room temperature. The unreacted zinc
powder was filtered off and the filtrate was collected, diluted
with diethyl ether and then washed twice with water. The ether
solution was dried with anhydrous MgSO.sub.4 and the solvent was
evaporated under reduced pressure. The crude product was
recrystallized from hexane to afford a greenish crystal in the
yield of 91% (15.3 g). .sup.1 H-NMR (CDCl.sub.3, ppm): .delta.7.40
(d, 2H, J=5 Hz), 7.11 (d, 2H, J=5 Hz).
3,3'-Dihexyl-2,2'-bithiophene
Hexylmagnesium bromide (100 ml, 2 M solution in diethyl ether, 200
mol) was added dropwise to a solution of
3,3'-dibromo-2,2'-bithiophene (15 g, 46.6 mmol) and
Ni(dppp)Cl.sub.2 (0.5 g, 0.1 mmol) in 100 ml of diethyl ether at
0.degree. C. The reaction was slightly exothermic and a red brown
coloration was observed. After stirred and heated for 24 h, the
reaction mixture was cautiously poured into a mixture of crushed
ice and diluted HCl solution and extracted with ether. The combined
extracts were dried over anhydrous MgSO.sub.4 and filtered. After
removal of the solvent, the residue was vacuum-distilled to give a
clear viscous oil (15.6 g, 81%). .sup.1 H-NMR (CDCl.sub.3, ppm):
.delta.7.25 (d, 2H, J=5 Hz), 6.96 (d, 2H, J=5 Hz), 2.50 (t, 4H),
1.54 (m, 4H), 1.23 (m, 12H), 0.85 (t, 6H).
5-(3,3'-Dihexyl-2,2'-bithienyl)methylphosphonate
A solution of 3,3'-dihexyl-2,2'-bithiophene (8 g, 24 mmol) in 80 ml
of anhydrous THF was added over 45 min under argon at -78.degree.
C. to a stirred solution of n-butyllithium (9.6 ml, 2.5 M in
hexanes, 24 mmol) in 150 ml of THF. The solution was stirred for 45
min at -78.degree. C., and then transferred, via cannula, into a
flask cooled to -20.degree. C. in a dry ice/CCl.sub.4 bath,
containing CuI (4.6 g, 24 mmol). After 2 h, diethyl
iodomethylphosphonate (6.7 g, 24 mmol) was added in one portion,
and the solution was reacted at room temperature overnight. The
dark reaction mixture was poured into 300 ml of ether and 200 ml of
water, and the organic layer washed successively with 3.times.200
ml water, 1.times.200 ml 5% aqueous NaHCO.sub.3, 2.times.200 ml
water, and 2.times.200 ml saturated brine solution. The organic
layer was dried (MgSO.sub.4), and evaporated. The resulting residue
was purified by column chromatography packed with silica gel (1:1
hexanes:ethyl acetate), affording a clear yellow viscous oil (7.2
g, 62%). .sup.1 H-NMR (CDCl.sub.3, ppm): .delta.7.26 (d, 1H, J=5
Hz), 6.96 (d, 1H, J=5 Hz), 6.88 (d, 1H, J=3.2 Hz), 4.12 (m, 4H),
3.34 (d, 2H, J=20.5 Hz), 2.47 (m, 4H), 1.52 (m, 4H), 1.31 (t, 6H),
1.24 (m, 12H), 0.86 (t, 6H).
5-(5'-Bromo-3,3'-dihexyl-2,2'-bithienyl)methylphosphonate
A solution of 5-(3,3'-dihexyl-2,2'-bithienyl)methylphosphonate (7
g, 14.5 mmol) and NBS (2.8 g, 15.7 mmol) in 150 ml of
dichloromethane was stirred at 0.degree. C. for 1 h and at room
temperature for 2 h. Then the mixture was washed with 100 ml of 10%
KOH aqueous solution and then with water until the solution was
neutral. The organic layer was concentrated to give the crude
product (7.8 g, 96%). .sup.1 H-NMR (CDCl.sub.3, ppm): .delta.6.90
(s, 1H), 6.84 (d, 1H, J=5 Hz), 4.10 (m, 4H), 3.30 (d, 2H, J=20.5
Hz), 2.43 (m, 4H), 1.50 (m, 4H), 1.29 (t, 6H), 1.22 (m, 12H), 0.85
(t, 6H)
5-[E-4-(N,N-Diethylamino)phenylene]-5'-bromo-3,3'-dihexyl-2,2'-bithiophene
To a solution of
5-(5'-bromo-3,3'-dihexyl-2,2'-bithienyl)methylphosphonate (7.5 g,
13.3 mmol) and potassium t-butoxide (1.7 g, 14.6 mmol) in 100 ml of
THF was added 4-(diethylamino)benzaldehyde (2.4 g, 13.3 mmol) in 20
ml of THF at 0.degree. C. during 30 min. This is stirred for 4 h
and normal workup gave a yellow viscous oil (7.0 g, 90%). .sup.1
H-NMR (CDCl.sub.3, ppm): .delta.7.32 (d, 2H, J=5 Hz), 6.90 (d, 1H,
J=7.5 Hz), 6.85 (s, 1H), 6.80 (s, 1H), 6.78 (d, 1H, J=7.5 Hz), 6.67
(d, 2H, J=5 Hz), 3.41 (q, 4H), 2.50 (t, 2H), 2.41 (t, 2H), 1.50 (m,
4H), 1.21 (m, 12H), 1.17 (t, 6H), 0.87 (t, 6H).
5-[E-4-(N,N-Diethylamino)phenylene]-5'-formyl-3,3'-dihexyl-2,2'-bithiophene
n-Butyllithium (12 ml, 2.5 M in hexanes, 30 mmol) was added
dropwise to a solution of
5-[E-4-(N,N-diethylamino)phenylene]-5'-bromo-3,3'-dihexyl-2,2'-bithiophene
(7 g, 12 mmol) in 80 ml of THF over 15 min at -78.degree. C. Then
the reaction mixture was allowed to gradually rise to -20.degree.
C. and 5 ml of anhydrous DMF was added. After the mixture was
stirred for 3 h, 50 ml of 1N HCl was added dropwise to terminate
the reaction. The normal workup was then carried out and the crude
product was purified by column chromatography over silica gel,
eluting with ethyl acetate/hexane (1:5) to afford a yellow viscous
oil (5.7 g, 89%). .sup.1 H-NMR (CDCl.sub.3, ppm): .delta.9.85 (s,
1H), 7.64 (s, 1H), 7.31 (d, 2H, J=5 Hz), 6.96 (d, 1H, J=7.5 Hz),
6.90 (s, 1H), 6.79 (d, 1H, J=7.5 Hz), 6.50 (d, 2H, J=5 Hz), 3.36
(q, 4H), 2.61 (t, 2H), 2.50 (t, 2H), 1.55 (m, 4H), 1.26 (m, 12H),
1.17 (t, 6H), 0.85 (t, 6H).
2-Dicyanomethylen-3-cyano-4-{5-[E-(4-N,N-diethylamino)phenylene-3,3'-dihexy
l-2,2'-bithien-5']-E-vinyl}-5,5-dimethyl-2,5-dihydrofuran
(Chromophore)
To a solution of sodium ethoxide (0.8 ml, 21 wt % solution in
ethanol) in 100 ml of ethanol was added
5-[E-4-(N,N-diethylamino)phenylene]-5'-formyl-3,3'-dihexyl-2,2'-bithiophen
e (5.7 g, 10.6 mmol) and
2-dicyanomethylen-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (2.6 g,
13.1 mmol). The reaction mixture was stirred and refluxed for 6 h.
When TLC indicated that the reaction was almost complete, the
mixture was cautiously poured into water and kept at 0.degree. C.
overnight. The crystalline precipitate was recrystallized from
ethanol to give shiny crystals of the chromophore (5.5 g, 72%).
.sup.1 H-NMR (CDCl.sub.3, ppm): .delta.7.80 (d, 2H, J=12.5 Hz),
7.40 (s, 1H), 7.34 (d, 1H, J=8 Hz), 6.95 (d, 1H, J=12.5 Hz), 6.88
(s, 1H), 6.82 (d, 1H, J=12.5 Hz), 6.65 (d, 1H, J=8 Hz), 6.53 (d,
2H, J=12.5 Hz), 3.38 (q, 4H), 2.62 (t, 2H), 2.55 (t, 2H), 1.76 (s,
6H), 1.57 (m, 4H), 1.27 (m, 12H), 1.18 (t, 6H), 0.87 (t, 6H).
Referring to FIG. 10, a representative bridge modification by
bithiophene insertion and dimethyldioxine ring modification is
illustrated. The resulting chromophore has an much improved
r.sub.33 of 95 pm/V at 1.06 .mu.m.
Several exemplary preferred ring-locked tricyano electron acceptor
groups are illustrated in FIG. 11. In FIG. 11, R.sub.1 to R.sub.9
=H, --C.sub.n H.sub.2n+1, n=1-30 including primary, secondary,
tertiary and any branched alkyl groups, or any alkyl group with
1-30 carbon atoms functionalized with one or more of the following
functional groups: hydroxy, ether, ester, amino, silyl, siloxy.
The five-membered-ring-locked tricyano acceptor (cyanofuran
acceptor, TCF in FIG. 11) has been modified to further increase
electro-optic activity and chromophore stability. According the
present invention, a large number of atoms and organic groups
(e.g., carbonyl) have been used in place of the furan oxygen in the
electron acceptor group leading to improved electrooptic and
optical properties. Six-membered-ring-locked analogs (TCP) have
also been developed. The oxygen atom of the furan ring and the
pyran ring (in TCF and TCP) is replaced by a methylene moiety to
produce the desired effect of blue shifting the optical absorption
spectrum leading to lower optical loss for some electrooptic
applications.
Referring to FIG. 12, a modified version of CLD is shown where the
cyanofuran acceptor has been modified by replacement of the furan
ring with an isophorone ring structure. This has the desired effect
of blue shifting the optical absorption spectrum leading to lower
optical loss for some electrooptic applications.
Synthesis of Chromophore with Isophorone Structure in Electron
Acceptor Group
To a mixture of isophorone (400 g), EtOH (1000 ml), NaOH (20 g) and
water (30 ml) was added 1.2 eq, 3.473 mol, 394.76 g of 30% H.sub.2
O.sub.2 in portions at RT. After 4 hour of stirring, the mixture
was neutralized with dilute acetic acid and extracted with diethyl
ether. The extract was dried over MgSO4, condensed via rotary
evaporation. The crude product was used in the next reaction
without purification.
To a solution of the above crude product in 500 ml EtOH was added a
solution of 2.89 mol, 108 g KCN/150 g water in portions over 0.5 h.
The mixture was refluxed for 1 h. Rotovap at 60.degree. C. to
remove EtOH. The residue was neutralized with 6N hydrochlorix acid.
The product was collected by filtration. The crude product was
purified with column chromatography using 4/1 hexanes/EtOAc as
eluent to give 180 g pure product.
TCI (2-cyano-3-dicyanomethylene-1,5,5-dimethylcyclohexene): A
mixture of 2-cyanoisophorone (14.19 g, 86.9 mmol), malononitrile
(6.89 g), EtOH (15 ml) and EtONa (100 mmol, 6.88 g) was heated in
80-90 C. bath for 1 h. The mixture was poured water, neutralized
with acetic acid and extracted with ethyl acetate. The extract was
condensed and purified with silica gel column chromatography.
Recrystallization of the product from EtOAc/hexane gave gray
crystals with mp of 103.5-105.5. Elemental analysis: calcd. C,
73.91; H, 6.20; N, 19.89; found C, 73.93; H, 6.26; N 19.97.
The chromophore (CLD-54) was synthesized in a manner similar to the
synthesis of chromophore CLD-1 in FIG. 2. UV-vis aborption: 600 nm
in dioxane, 663 nm in chloroform.
Referring to FIG. 13, alternative donor structures for the FTC,
CLD, GLD and ZLD chromophores are illustrated. It has been observed
that chromophores of the FTC, CLD, GLD and ZLD type have been
systematically improved by the utilization of the new donor
structures which provide improved electrooptic activity as the
result of an improved inductive (electron donating) effect and
through better overlap of .pi.-electron orbitals due to steric and
resonance effects. Exemplary FTC chromophore structures with
modified donor structures are illustrated in FIGS. 14A and 14B. All
of these structures have been incorporated into a variety of
polymer lattices. In FIG. 13, R.sub.1 to R.sub.2 =H, --C.sub.n
H.sub.2n+1, n=1-30 including primary, secondary, tertiary and any
branched alkyl groups, or any alkyl group with 1-30 carbon atoms
functionalized with one or more of the following functional groups:
hydroxy, ether, ester, amino, silyl, siloxy.
Preparation of a Polyester Containing CLD-5 Chromophore
All chromophores functionalized with reactive groups have been
incorporated into a variety of polymer lattices by reacting them
with various polymerization and polymerization coupling reagents.
Such structures exhibit excellent thermal stability (i.e., no loss
of electrooptic activity to greater than 100.degree. C.). The
preparation of a polyester containing CLD-5 chromophore is
illustrated in FIG. 15 and discussed below.
Preparation of 19.6 wt % CLD-5 Loaded Polyester
In dry box, a mixture of 0.4 mmol of terephthaloyl dichloride,
0.0838 mmol CLD-5, 2 ml THF and 0.1 mmol of triethylamine was
stirred at 30.degree. C. for 10 h. Then 0.366 mmol of
isopropylidenediphenol and 0.69 mmol of triethylamine were added.
Stirring was continued for 26 h later and the mixture was
precipitated from MeOH. The polymer was dissolved in methylene
chloride and reprecipitated by dropping the solution into methanol.
The product was collected by filtration and dried in vacuo.
Continued improvement in theoretical tools used to guide the design
of improved electrooptic materials has also been made. Monte Carlo
Molecular Dynamical Methods as well as equilibrium statistical
mechanical methods have been developed to guide the design of
improved materials. As shown in FIG. 16, these various methods give
comparable results. More specifically, a comparison of equilibrium
and molecular dynamical (Monte Carlo) calculations is provided. The
solid lines are the equilibrium statistical mechanical results
while the Monte Carlo results are given by connected dots. The
variation of electrooptic activity (divided by molecular
polarizability) versus chromophore concentration in the polymer
lattice is given for two values of the electric poling field. For
the lower field value, the Monte Carlo results are displaced
downward to make comparison of the functional dependence more
easily visualized.
The organic chromophores of the present invention exhibit
exceptional molecular optical nonlinearity, thermal stability, and
low optical absorption at telecommunication wavelengths. The
chromophore materials of the present invention are suitable for
processing into hardened polymers for electrooptic devices
employing protocols previously developed for other chromophores.
The materials are fully amenable to all processing steps necessary
for the fabrication of such devices.
According to the present invention, these materials can be employed
not only in conventional electrooptic modulator device
configurations but also in devices employing a constant bias field
which permits the full potential of the materials to be
demonstrated. Referring to FIG. 17, an exemplary preferred
electrooptic device 1700 employing a constant electric field bias
is illustrated. The illustrated electrooptic device 1700 includes a
modulator chip 1702, a fiber 1704, a thermoelectric cooler 1706, a
temperature controller 1708, a thermister 1710, and a bias tee 1712
(including a resistor and a capacitor) configured as shown
providing a light output indicated by arrow 1714.
Referring to FIG. 18, an exemplary preferred Mach Zehnder modulator
1800 incorporating a chromophore material of the present invention
is illustrated. The illustrated modulator 1800 includes a Si
substrate 1802, an Epoxylite (3 .mu.m) layer 1804, a PU-chromophore
(1.5 .mu.m) layer 1806, a NOA73 (3.5 .mu.m) layer 1808, a waveguide
1810 and an electrode 1812 configured as shown with light indicated
by arrows 1814, 1816.
Referring to FIG. 19, the materials of the present invention are
shown in the form of microstrip lines in an exemplary preferred
microwave phase shifter 1900 of the type employed in optically
controlled phase array radars. The illustrated microwave phase
shifter 1900 includes microstrip lines 1902, 1904, a DC control
electrode 1906, a DC source 1908, a photodetector 1910 and an
optical waveguide 1912 configured as shown with light indicated by
arrow 1914.
Those skilled in the art will appreciate that various adaptations
and modifications of the just described preferred embodiment can be
configured without departing from the scope and spirit of the
invention. Therefore, it is to be understood that, within the scope
of the appended claims, the invention may be practiced other than
as specifically described herein.
* * * * *